Cummins ISF3.8 Specifications
| Engine Model: Cummins ISF3.8 |
| Engine Type: 4-cycle inline 4-cylinder common-rail direct injection liquid-cooled diesel |
| Total Displacement: 229 cu.in (3.76 L) |
| Rated Engine Power: 80-170 Hp (60-127 kW) at 2600 rpm |
| Aspiration Type: Turbocharged |
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The Cummins ISF3.8 is a compact, modern,
high-efficiency 3.8-liter inline-four diesel engine designed for light-
and medium-duty trucks, buses, off-road machinery, and industrial
equipment. As part of the Cummins F-Series platform, the ISF3.8 combines
advanced fuel-system technology, robust cast-iron construction,
electronic engine management, and emissions compliance up to Euro-6
(depending on configuration). It is known for low fuel consumption,
strong low-RPM torque, high power-to-weight ratio, and exceptional
durability in harsh operating conditions.
The ISF3.8 uses a high-pressure common-rail (HPCR) fuel-injection
system, electronic control module (ECM), advanced turbocharging, and
(depending on the variant) EGR, DOC, DPF, and SCR after-treatment. The
compact footprint makes it popular among vehicle manufacturers and
mobile-equipment builders requiring a reliable, efficient engine with
low maintenance requirements.
The Cummins ISF3.8 is a four-stroke, water-cooled, turbocharged
inline-four diesel engine. Displacement is 3.76 liters (229 cubic
inches). Bore is 102 mm (4.02 in), stroke is 115 mm (4.53 in), forming a
long-stroke geometry optimized for torque delivery. Compression ratio
ranges from 16.5:1 to 17.2:1 depending on emissions rating and
calibration.
Power ratings vary widely across
applications:
– Light trucks: 130–170 hp (97–127 kW) @ 2,600–3,200 rpm
– Vans and buses: 120–160 hp (89–119 kW) @ 2,200–2,600 rpm
– Off-road/industrial: 80–140 hp (60–104 kW) @ 2,200–2,600 rpm
– Peak torque: 450–600 Nm (332–443 lb-ft) @ 1,200–1,800 rpm
Idle speed: 700–800 rpm
Governed speed: 2,800–3,200 rpm
Firing order: 1-3-4-2.
The forged-steel crankshaft is supported by five main bearings. Pistons
are cast aluminum with reinforced crowns and internal cooling galleries.
Connecting rods are forged steel. The camshaft is gear-driven for
lifetime timing stability and minimal maintenance.
The ISF3.8 uses a cast-iron block with:
– Parent-bore cylinders
– Deep-skirt design for rigidity
– Structural ribs for vibration control
– Full water-jacket cooling around cylinders
– Wide main-bearing saddles
The block is engineered for high durability under prolonged high-load
use and accommodates multiple re-boring operations.
The cast-iron cylinder head includes:
– Four valves per cylinder (16-valve configuration)
– Central injector placement
– Hardened valve seats and guides
– Roller tappets and pushrods
– High-flow intake and exhaust ports
Cold valve-lash settings:
– Intake: 0.20–0.30 mm (0.008–0.012 in)
– Exhaust: 0.45–0.55 mm (0.018–0.022 in).
The engine uses a high-pressure common-rail (HPCR) fuel-injection system
designed for high efficiency and low emissions.
Key components:
– High-pressure fuel pump (typically 1,600–1,800 bar / 23,000–26,000
psi)
– Electronically controlled injectors
– Electric lift pump
– Dual-stage filtration (primary + secondary)
– Water separator
– Rail-pressure, temperature, and supply sensors
Injection events include pilot, main, and post-injection for noise
reduction and emissions control.
Fuel-system maintenance:
– Replace fuel filters every 250–300 hr
– Drain separator daily
– Injector testing every 1,200–1,800 hr
– HPCR pump inspection at major overhaul intervals.
The ISF3.8 uses a full-pressure wet-sump lubrication system with a
gear-driven oil pump.
Oil capacity: 7–10 liters (7.4–10.6 qt)
Oil pressure:
– Operating: 275–380 kPa (40–55 psi)
– Idle: 70–100 kPa (10–15 psi)
Recommended oil:
– SAE 10W-30 or 15W-40
– API CI-4, CJ-4, CK-4 or ACEA E9
Oil-change interval:
– Industrial: 250–500 hr
– Automotive: up to 20,000 km depending on use.
The cooling system includes:
– Belt-driven centrifugal water pump
– Thermostat-regulated coolant flow
– Full-coverage coolant passages
– Integrated oil cooler
– Radiator or remote-cooling option
Thermostat:
– Begins opening: 82°C (180°F)
– Fully open: 95°C (203°F)
Cooling capacity: 12–16 liters (12.7–17 qt)
System pressure: 70–100 kPa (10–15 psi).
| Intake and Exhaust Systems |
Intake system:
– Dry-type filters
– Optional dual-stage filtration
– Optional cyclone pre-cleaner
Turbocharging:
– Wastegate turbocharger or VGT depending on version
– Oil-lubricated core
– High-flow compressor design
Aftercooling:
– Air-to-air charge-air cooler (ATAAC) standard on most models
Exhaust:
– Cast-iron manifold
– Optional:
- EGR cooler
- Diesel oxidation catalyst (DOC)
- Diesel particulate filter (DPF)
- Selective catalytic reduction (SCR).
| Electrical and Electronic Systems |
An advanced ECM (Electronic Control Module)
manages:
– Injection timing and pressure
– Turbocharger operation
– EGR valve (if equipped)
– DPF regeneration cycles
– SCR/DEF dosing
– Idle control
– Diagnostic and fault-logging
Sensors include:
– Crankshaft and camshaft position
– MAP/boost
– Oil pressure and temperature
– Coolant temperature
– Fuel temperature and pressure
– EGT sensors (multiple locations)
– DEF level and quality (SCR engines)
– NOx sensors
Electrical system:
– 12V or 24V starting systems
– Alternator: 70–120 amps.
Available equipment includes:
– PTO drive pads
– Hydraulic pump mounts
– Remote radiator kits
– Belt-drive accessory packages
– Air-conditioning compressor mounts
– Vehicle-specific installation packages.
Approximate dimensions:
– Length: 780–900 mm (31–35 in)
– Width: 650–760 mm (26–30 in)
– Height: 830–950 mm (33–37 in)
Dry weight: 250–335 kg (551–738 lb).
Recommended service intervals:
– Oil and filter: 250–500 hr
– Fuel filters: 250–300 hr
– Air filter: inspect every 50–100 hr
– Valve-lash: every 1,000 hr
– Injector testing: 1,200–1,800 hr
– Coolant replacement: every 2 years
– Belt inspection: each service
– Compression testing: 2,000 hr.
– Cylinder head bolts: 150–170 Nm (111–125 lb-ft) + angle torque
– Main-bearing caps: 175–190 Nm (129–140 lb-ft)
– Connecting rods: 65–75 Nm (48–55 lb-ft)
– Flywheel bolts: 100–120 Nm (74–89 lb-ft)
– Crankshaft damper bolt: 200–225 Nm (148–166 lb-ft)
– Oil drain plug: 40–50 Nm (30–37 lb-ft)
– Injector hold-down: 20–25 Nm (15–18 lb-ft).
The Cummins ISF3.8 is used in:
– Light/medium trucks
– Delivery vans
– Small buses and minibuses
– Agricultural tractors
– Loaders, telehandlers, and construction equipment
– Municipal vehicles (sweepers, utility trucks)
– Industrial pumps and compressors
– Power units and stationary machinery
– Custom OEM machinery platforms.
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